The present invention relates to an air conditioner and, more particularly, to an air conditioner which has a refrigeration cycle with a compressor of variable capacity.
Since an air conditioner which forms a refrigeration cycle of heat pump type can readily switch between room cooling and room heating operations, the conditioner is frequently used. However, a conventional compressor, which is used in a refrigeration cycle, always has a constant capacity and hence a constant exhaust amount and cannot, accordingly, operate in response to the load state in the refrigeration cycle. Consequently, the compressor cannot efficiently produce the refrigeration capacity of the refrigeration cycle.
Therefore, a compressor of the variable capacity type, i.e., variable exhaust amount type using 2-stage compression, pole change conversion, gas injection, liquid injection or release is employed as means for improving the room cooling or room heating capacity of the refrigeration cycle. Further, it has recently been proposed that the operating frequency of a compressor be controlled by an inverter, thereby varying the amount of the refrigerant to be exhausted from the compressor. The compressors of these types can adjust the exhaust amount in response to the load state of the refrigeration cycle, with the result that the room cooling or heating capacity of the refrigeration cycle as well as the energy-saving effect of the compressor can be improved.
In the refrigeration cycle having the compressor of this type, the exhaust amount of the compressor is variable, but the refrigerant temperature, discharged from the compressor, is controlled so as to always be constant. However, it is understood that the temperature of the exhausted refrigerant largely affects the influences of the room cooling or heating capacity of the refrigeration cycle. Accordingly, when the exhaust temperature of the refrigerant is always constant, the maximum capacity of the refrigeration cycle, responsive to the operating state of the compressor, cannot be performed, energy is used to drive the commpressor is an uneconomical manner, and the room cooling or heating efficiency of the refrigeration cycle frequently decreases.